Treatment of hydrocarbon oils



Patented July 28, 1936 UNITED STATES PATENT @FFEQE TREATMENT OF HYDROC'ARBON OILS ware No Drawing.

Serial No. 564,961. 1935 9 Claims.

This invention relates to the treatment of hydrocarbon oils and refers more particularly to the treatment of the lighter distillates produced in the cracking of heavier oils although similar distillates produced from the primary or noncracking distillation of crude petroleums may also be treated.

More specifically, the invention relates to the treatment of such hydrocarbon mixtures while in a heated vaporous condition, a process being disclosed which accomplishes the necessary refining of such vapors prior to their condensation and substantially eliminates the necessity for extensive treatment of the distillates and their subsequent rerunning, thus eflecting much needed economies.

It has been recognized for some time by those engaged in the oil industry that the usual method of treating cracked distillates with sulphuric acid followed by neutralization and rerunning to produce end point gasoline possessed numerous in-- herent disadvantages due principally to the need for special auxiliary treating equipment and the necessity of rerunning the treated distillates,

' since even though distillates of gasoline end point were treated their rerunning was usually necessary on account of the formation of high boiling polymers, sulfoxy compounds, sulphuric acid derivatives, etc., which raise the final boiling point of the gasoline and render it unstable with respect to color and gum formation. Of the proposed Vapor phase treating methods thus far tried a few are attaining commercial status, notably treatments with solid adsorbents such as fullers earth, and metallic compounds have been used with some success for desulphurizing purposes. As yet, however, it cannot be said that any one type of vapor phase treatment has been found which is efiioient enough to completely supersede the customary acid treating and rerunning of crackeddistillates. The present invention provides an improvement over existing commercial processes which possesses markedadvantages over those now in vogue, its details being set forth in the following paragraphs;

In one specific embodiment the invention comprises treating hydrocarbon oil vapors, particularly cracked hydrocarbon oil vapors, with aqueous solutions containing sulphuric acid and organic bases.

The feature of the invention is thus to accomplish sulphuric acid treatment of hydrocarbon oil Vapor by using solutions of sulphuric acid whose reactivity is moderated or tempered by the presence of neutral compounds-of organic bases and Application September 24, 1931,

Renewed September 20,

sulphuric acid, as opposed to the use of dilute aqueous sulphuric acid, the range of use of the latter being limited due to the fact that under the conditions of temperature and pressure common to fractionators which are handling cracked vapors that any dilute aqueous sulphuric acid which may be added thereto is rapidly concentrated to a strength which is undesirable because of its powerful oxidizing and charring eiiect, producing thus cokey sludges and too severe an effect upon the vapors. The, use of the organic salts with sulphuric acid has the effect of diluting the sulphuric acid with substances having a low vapor pressure so that the strength and composition of the treating solution is not appreciably changed during the treatment.

As examples of organic bases whose sulphuric acid salts may be used along with sulphuric acid and treatments characteristic of the process are such substances as amines, imines, pyridines, picolines, lutidines, collidines, etc. Of the amines, aniline is a good example, this substance yielding under certain conditions of treatment sulfanilic and metanilic acids which act as the diluting or spacing materials. Pyridine and its homologs may also undergo a certain degree of sulfonation, depending upon the strength of the sulphuric acid employed and the operating conditions of temperature and pressure. It is generally preferred to use organic bases of ring structure, as the object of the treatment of the invention is toselectively remove more highly unsaturated olefin compounds from cracked vapors and to some extent the sulphur compounds. It has been found that when the acid is diluted with alkyl derivatives of sulphuric acid such as ethyl sulphuric acid, dimethyl sulphate, etc., that the reactivity of the solution may be lessened to an undesirable degree.

While in most cases the virtue of the treating solution employed is due principally to the sulphuric acid, it is recognized that the other dissolved compounds may at times exert a definite chemical influence upon the reactions other than merely moderating the effect of the sulphuric acid. It will be also evident that the selection of any particular compound or mixture of compounds for use with the sulphuric acid will be determined by solubility relations, the extent of refining treatment necessary upon the vapors, the general operating conditions and the matter of economy in the cost of the reagents. However, such problems will be solved by those familiar with the treating art without great difiiculty.

The process may be conducted in any type of apparatus suitable for efliciently contacting vapors with liquid treating reagents. A filled tower containing crushed rock, fragments of porcelain, Raschig rings or metallic filler is readily utilizable, the scheme of operation in such a case being to pass the vapors upwardly through the tower countercurrent to the descending treating solution which has been introduced above the bafliing material through distributing means to assist in securing intimate contact of oil vapors and liquid. At other times greater advantage may be gained by passing the vapors downwardly along with the treating solution, this serving in some instances to allow better separation and disposition of sludge and heavy reaction products. Treatments of high efficiency may be obtained by utilizing towers of the spaced-tray type, the trays being perforated or supporting bubble caps such as are commonly employed in fractionating towers in the oil industry. Towers may be lined with lead or other materials to minimize corrosion effects or suitably chosen corrosion resisting metals may be employed in their construction.

Another type of operation which may be successfully employed involves the simple expedient of merely allowing the vapors to rise through a pool of treating solution, the solution being circulated to insure thorough mixing and used until substantially spent, at which time the vapors undergoing treatment may be diverted to a fresh supply of reagent in parallel connected towers, thus insuring subtantially continuous operation.

Owing to the possibility of varying the composition of the treating solutions over a wide range, the process is adaptable for use under practically all conditions of temperature and pressure encountered in cracking, primary distilling or rerunning operations upon vapors containing large amounts of gasoline boiling range fractions. The temperatures prevailing in such distillations are usually included within the range of 200 to 600 F. and pressures from atmospheric or slightly superatmospheric to high superatmospheric such as for example pressures in the neighborhood of 300 pounds per square inch or higher.

Treatments may be employed alone or in combination with other types of vapor phase treatment. For example, the vapors may be treated with ammonia or alkali solutions to neutralize and remove hydrogen sulphide, after which the process of the invention is applied and vapors after the treatment may be further neutralized, subjected to filtering or sedimentation to remove entrained particles or further neutralized and filtered to remove substantially all acidic reaction products. While it is contemplated that the process of the invention is in general sufficient to produce finished gasoline from cracked vapors in one step it may be at times necessary to subject the condensed gasoline to a mild neutralizing action which is easily accomplished by injecting minor amounts of a solution of caustic soda into the rundown line to storage, or to other separate treatments.

Treatments may be employed alone or in combination with other types of vapor phase treatment. For example, the vapors may be treated with ammonia or alkali solutions to neutralize and remove hydrogen sulphide, after which the process of the invention is applied and vapors after the treatment may be further neutralized, subjected to filtering or sedimentation to remove entrained particles or further neutralized and filtered to remove substantially all acidic reaction products. While it is contemplated that the process of the invention is in general sufficient to produce finished gasoline from cracked vapors in one step it may be at times necessary to subject the condensed gasoline to a mild neutralizing action which is easily accomplished by injecting minor amounts of a solution of caustic soda into the rundown line to storage, or to other separate treatments.

The vapors treated may receive sufficient fractionation during the treatment depending upon the type and capacity of treating tower employed or they may be subsequently fractionated in separate equipment, with return of intermediate refluxes to the primary cracking stage for further conversion.

The sludges produced by the process of the invention will also vary in character depending upon the numerous factors entering into the treatment and the steps necessary for their recovery for further use will necessarily be modifled accordingly. In most instances thegeneral procedure commonly employed in recovering sludge from liquid phase sulphuric acid treatments is applicable, the sludge being diluted to a proper point with water to cause separation of oily material, and the aqueous solution being concentrated and receiving further addition of chemicals to restore it to the proper composition for use. It is contemplated to continuously regenerate used treating solutions as a step in the treating process.

Numerous examples of operation and the results obtainable therefrom might be given but a few will suffice to indicate the feasibility of the operation from a commercial standpoint. As one example of operation, the gasoline range boiling vapors from a cracking process operating upon a Mid-Continent residuum may be passed under pressure of approximately 50 pounds per square inch counterflow to a descending solution containing approximately 40% of sulphuric acid, 30% i effect of the treatment:

Raw gaso- Treated ine gasolinelf z Gravity A. P. I 55.0 55. 4 Final B. P 400 F. 400 F. Color, Saybolt Yellow +30 Color after 4 hrs. exposure 26 Gums, mgJlOO cc 410 18 Snlnhnr 0. 25 0. 10

The continuous regeneration of treating solution from the sludge produced in the preceding example, and the circulation of reagent through the tower to enable its eificient utilization may make possible the treatment to the point shown in the tabulation by using as low as 5 pounds of reagent solution per barrel of gasoline, which is well within the required economy since the sulfanilic acid is substantially unaffected in the treating and regenerating steps so that the only Raw gaso- Treated ine gasoline Gravity A. P. I 53.8 54. 2 Final B. P 405 406 Color, Saybolt 12 30 Color after 4 hrs. exposure- Yellow 25 Gums, ing/ cc 550 20 Sulphur 0. 41 0. 15

The foregoing specification and examples have sufiiciently disclosed and illustrated the process of the invention and made its features and. advantages evident in comparison with existing processes. While the description and examples are accurate, the invention is not confined thereto but includes many other examples and modes of operation within its generally broad scope though it has not been deemed necessary to go into further detail for purposes of disclosure.

I claim as my invention:

1. In the refining of cracked hydrocarbon distillate, the step which comprises treating the distillate in vapor form with an aqueous solution predominating in sulphuric acid to which has been added an amine capable of and in amount sufficient to substantially reduce the reactivity of the acid.

2. In the refining of cracked hydrocarbon distillate, the step which comprises treating the distillate in vapor form with sulphuric acid to which has been added aniline in amount sufficient to substantially reduce the reactivity of the acid.

3. In the removal of sulphur and gum-forming unsaturated hydrocarbons from cracked petroleum distillates, the step which comprises treating the cracked petroleum distillate in vapor form with aqueous sulphuric acid solution to which has been added an organic base capable of and in amount sufficient to substantially reduce the reactivity of the acid.

4. In the removal of sulphur and gum-forming unsaturated hydrocarbons from cracked petroleum distillates, the step which comprises treating the cracked petroleum distillate in vapor form with aqueous sulphuric acid solution to which has been added an organic nitrogeneous base capable of and in amount sufficient to substantially reduce the reactivity of the acid.

5. In the removal of sulphur and gum-forming unsaturated hydrocarbons from cracked petroleum distillates, the step which comprises treating the cracked petroleum distillate in vapor form with aqueous sulphuric acid solution to which has been added an organic base of ring structure capable of and in amount suificient to substantially reduce the reactivity of the acid.

6. In the removal of sulphur and gum-forming unsaturated hydrocarbons from cracked petroleum distillates, the step which comprises treating the cracked petroleum distillate in vapor form with aqueous sulphuric acid solution to which has been added an amine capable of and in amount suificient to substantially reduce the reactivity of the acid.

7. In the removal of sulphur and gum-forming unsaturated hydrocarbons from cracked petroleum distillates, the step which comprises treating the cracked petroleum distillate in vapor form with aqueous sulphuric acid solution to which has been added aniline in amount sumcient to substantially reduce the reactivity of the acid.

8. In the removal of sulphur and gum-forming unsaturated hydrocarbons from cracked petroleum distillates, the step which comprises treating the cracked petroleum distillate in vapor form with aqueous sulphuric acid solution containing sulfanilic acid in amount suflicient to substantially reduce the reactivity of the sulphuric acid.

9. In the removal of sulphur and gum-forming unsaturated hydrocarbons from cracked petroleum distillates, the step which comprises treating the cracked petroleum distillate in vapor form with aqueous sulphuric acid solution to which has been added pyridine in amount suificient to substantially reduce the reactivity of the acid.

JACQUE C. MORRELL. 

